1. Field of the Invention
The present invention relates to communication systems. More particularly, the present invention relates to a system and method for user identity portability in communication systems.
2. Background Information
Number portability can be used in telecommunications to allow users to move or otherwise switch operators and retain their phone number. For example, in a mobile network, a user with a particular Mobile Station International Subscriber Directory Number (MSISDN) can switch telecommunication services from one Mobile Network Operator (MNO) to another MNO, and retain their MSISDN. An “operator” is a network operator that provides communication capabilities in fixed, mobile, converged, or other appropriate types of networks. The operators offer services with suitable service enablers that provide the communication services to users. Users “belong” or subscribe to or are otherwise affiliated with the operators, and consume communication services using the respective operator's service enablers.
An ENUM (tElephone NUmber Mapping) server provides the ability to map E.164 phone numbers to a corresponding Uniform Resource Identifier (URI). Such telephone number mapping is described in, for example, Internet Engineering Task Force (IETF), Network Working Group, Request for Comments (RFC) 3761, “The E.164 to Uniform Resource Identifier (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)” (April 2004). E.164 phone numbering is described in, for example, Telecommunication Standardization Section of International Telecommunication Union (ITU-T) Recommendation E.164, “The International Public Telecommunication Numbering Plan” (February 2005).
Different services allow mapping to different forms of URIs, such as, for example, Session Initiation Protocol (SIP) URIs, Presence URIs, Instant Messaging (IM) URIs, Simple Mail Transfer Protocol (SMTP) URIs, and the like. For example, SIP URIs are discussed in IETF, Network Working Group, RFC 3969, “The Internet Assigned Number Authority (IANA) Uniform Resource Identifier (URI) Parameter Registry for the Session Initiation Protocol (SIP)” (December 2004). Presence URIs are discussed in, for example, IETF, Network Working Group, RFC 3953, “Telephone Number Mapping (ENUM) Service Registration for Presence Services” (January 2005), and Presence and IM URIs are discussed in, for example, IETF, Network Working Group, RFC 3861, “Address Resolution for Instant Messaging and Presence” (August 2004). Telephone URIs are discussed in, for example, IETF, Network Working Group, RFC 3966, “The tel URI for Telephone Numbers” (December 2004). Additionally, “eXtensible Resource Identifier” (“XRI”) is a scheme and resolution protocol for abstract identifiers developed by the XRI Technical Committee at the Organization for the Advancement of Structured Information Standards (OASIS) that can use, for example, “i-names” as user-friendly identifiers. Such mapping allows communication services that are based on phone numbers (e.g., MSISDN) to locate the corresponding URI. If the user retains their MSISDN when switching operators, the updated URI can reflect the correct addressing for the given user. Consequently, service enablers or mediation servers (such as messaging enablers) that consult or otherwise query the ENUM server can correctly route a message to the target, even if the user has switched operators.
For example, FIG. 1 is a diagram illustrating a message flow for a communication transaction between User A and User B belonging to different operators. In FIG. 1, User A desires to send a communication to User B at a certain MSISDN. In step 1, the communication is transmitted to the service enabler 105 for User A, including the destination information (User B at MSISDN). In step 2, the service enabler 105 determines that User B is a remote user (e.g., based on the MSISDN of User B). Accordingly, in step 3, the service enabler 105 initiates a search for address information for User B by forwarding an appropriate query (with the MSISDN of User B) to an interconnection node 110 that interconnects the networks of the operators for User A and User B. To resolve the query, the interconnection node 110 sends an ENUM query (with the MSISDN of User B) to ENUM server 115 in step 4. In response, the ENUM server 115 returns the URI of User B back to the interconnection node 110 in step 5. In step 6, the interconnection node 110 sends a request to the ENUM server 115 to resolve the domain of User B with the returned URI. In step 7, the ENUM server 115 responds with the IP address of the service enabler 120 of User B. Using such address information, the interconnection node 110 can forward User A's communication (with the URI of User B) to the service enabler 120 of User B in step 8. In step 9, the service enabler 120 for User B can forward the communication to User B at the indicated URI. Accordingly, User B can change operators, and User A can still communicate with User B if User A knows the MSISDN of User B.
The communication services provided by operators can incorporate communication contacts that identify the user with a known network identity to allow third parties to contact the user. However, if a user switches operators (and, for example, switches telephone numbers), then the user may need to change their network identity. Therefore, there is a need to allow a user to switch operators and retain their network identity.